November 9, 2026
Mini Splits for Casitas and ADUs: Sizing, Cost and What to Expect in Texas
Why mini splits are the usual choice for casitas and ADUs, how to size one for Texas heat, and what installation typically costs.
A mini split is the most common way to heat and cool a casita or ADU. You don't have to run ductwork from the main house, the space gets its own thermostat, and a small, efficient system can handle a Texas summer without driving up your power bill.
Why not tie into the main house's AC?
Extending ductwork from the main house to a detached casita is expensive, loses a lot of cool air along the way, and can overload a system that was sized for the main house only. A separate mini split avoids all of that. Whoever lives in the casita controls their own temperature, and the main house isn't affected.
How big a system does a casita need?
Most casitas and ADUs are 300–600 square feet. In Texas heat, that usually means a system between 12,000 and 18,000 BTU. The right size also depends on ceiling height, insulation and how much afternoon sun the space gets. An oversized unit costs more and doesn't control humidity well, so bigger isn't better.
Try our estimate calculator to get a size and price range for your space.
One unit or two?
A studio casita with one open room usually needs one indoor unit. If the casita has a separate bedroom with a door, a multi-zone system puts an indoor unit in each room, both connected to one outdoor unit, so each room stays comfortable.
What it costs
For a single-zone system in a typical Texas casita, installed prices usually fall in these ranges:
| Casita size | Typical installed price |
|---|---|
| 200–400 sq ft | $2,000–$4,000 |
| 400–600 sq ft | $2,300–$4,400 |
| 600–800 sq ft | $2,600–$4,900 |
If the casita doesn't already have a dedicated circuit for the system, adding one usually costs another $300–$1,200. Multi-zone systems cost more. We'll give you an exact price after seeing the space.
Permits and electrical
Most Texas cities require a permit for a new heating and cooling system, and the mini split needs its own electrical circuit. If you're building a new casita, plan the circuit and the outdoor unit's location with your builder early. It's easier than adding them later.
Renting your casita?
If you rent your casita to long-term tenants or short-term guests, a mini split is a selling point. Guests control their own temperature with a remote, it runs quietly, and you can set it to a reasonable temperature between stays.
Get a quote
We install mini splits in casitas, ADUs and guest houses across Texas. See our ADU & guest house service, or contact us for a free estimate.